1. Field of the Invention
The present invention relates to a hub of a magnetic tape cassette. More particularly, it relates to an improvement of a magnetic-tape clamp for securing a magnetic tape to a reel in magnetic tape cassette.
Various types of clamping means have been used for securing a magnetic tape or a leader tape to the reel of a magnetic tape cassette etc. The clamping of the magnetic tape requires that the clamping force should be sufficiently large, the outer periphery of the clamping member should have the same curvature as that of the hub of a reel and a step should not be formed between the ends of the clamping member and the reel.
FIGS. 1 and 2 show two types of magnetic-tape clamps which fairly satisfy the factors above described among the conventional type clamps (Japanese Utility Model Application No. 154953/1979). The clamp (2) shown in FIG. 1 or 2, made of plastic material having resiliency, is fitted into the recess of a hub (1) to clamp a magnetic tape or a leader tape (8) between the clamp (2) and the surface of the recess, thus the clamping of the magnetic tape is performed. The clamp (2) comprises an upper rib (3) having a circular-arc surface with the same curvature as that of the outer periphery of the hub (1), a pair of legs (4), (4) formed at both ends of the circular-arc and outer projections (5), (5) extending from the ends of the legs respectively. These outer projections (5), (5) are fitted into the grooves formed in the side walls of the hub (1) to clamp the magnetic tape. In order to increase the clamping force, a resilient lower rib (6) is utilized in the clamp shown in FIG. 1 and an inserting body (7) as a separate member is used in the clamp shown in FIG. 2. The conventional clamp has the disadvantage in that when the magnetic tape is forcibly pulled with a force greater than that given depending on the resiliencies of the legs (4), (4) and the lower rib (6), the magnetic tape is drawn out from the clamp (FIG. 1) or the using of the separate inserting body (7) causes an inconvenient fitting and has a tendency of easily dropping-out (FIG. 2).